1. Field of the Invention
The present invention relates to a method of controlling the movement of a teeming ladle and to a teeming machine for carrying out the method.
Existing automatic foundry installations for the repeated controlled filling of liquid metals from a tiltable ladle into successively furnished moulds function in the following manner: the molten mass during the teeming runs via a spout stone of radius R out of the ladle, wherein the tilting axis of the ladle extends at least approximately through the centre of this radius, the so called theoretical point of rotation of the spout, such that independently of the tilting angle of the ladle approximately equal geometric and thus flow design relationships are to be achieved. The tilting is effected via a controlled drive which via mechanical connection members engages the ladle.
With such installations one achieves an excellent running of the teeming procedure when teeming, during the teeming and at the completion of this. However, such installations suffer from the disadvantage for teeming at a relatively low teeming height the teeming funnel must lie near the edge of the mould box. With teeming funnels positioned further inside and whilst maintaining the required defined safety distance of the ladle body with respect to the mould box, the teeming height increases because of the segment shape of the teeming ladle.
Since teeming funnels positioned far inside the mould box may not be reached in a satisfactory manner, the funnel must be pulled to the edge which with existing models leads to costly modifications. In moulding boxes with weighting iron, the weighting iron must often be modified which again leads to additional costs. However since on the models or weighting irons, changes may not always be carried out, on account of the high teeming height one may only teem with an extended teeming spout. Such a teeming spout is however not suitable for the automatic teeming and with manual teeming can be handled only with difficulty.
From EP Patent 592 365 there is known a teeming method in which the teeming ladle, after the first teeming operation, and because of a stationary tilting axis may be displayed further towards the middle of the teeming mould, whilst maintaining a certain safety distance of the teeming ladle with respect to the teeming box. With this method the stationary tilting axis with the lift drive is attached at the front on the teeming spout and since the tilting bearing required on the tilting axis must likewise be located at a safety distance over the teeming box or the weighting iron, this leads by way of design likewise to a large teeming height. A large teeming height however causes considerable disadvantages; since more kinetic energy must be destroyed a deeper teeming funnel becomes necessary so that the top box may not be optimally exploited. Furthermore more circulation material is required, there is more splatter iron, a more erratic teeming with more turbulence in the funnel, and more sand rinsings and more sand and gas enclosures are to be expected. With mould boxes with weighting iron the teeming height is increased further since the tilting bearing must lie above the weighting iron.
It is thus an object of the invention to avoid all mentioned disadvantages and to provide a method and a teeming machine for controlling the movement of a teeming ladle, with which one may always teem at a lower teeming height even when the teeming funnels are arranged at any location in the mould box, and with which the theoretical point of rotation of the spout is stably guided into the lowest possible position. This object is achieved by the method and the teeming machine as hereinafter set forth in greater detail.